**3. Micro-morphological features**

Stomata are the important anatomical and physiological characteristics of a leaf which control the rate of CO2 movement from air to the chlorophyllus tissue within the leaf and thereby influence the rate of CO2 exchange [10]. Stomatal size and frequency are important parameters in selecting drought resistant genotypes and these are also believed to regulate the leaf yield. As such, the Stomatal frequency has been studied in these taxa to correlate with cytological information recorded in the

**9**

*Studies on Basic Chromosome Number, Ploidy Level, Chromosomal Association…*

in tetraploid when compared to triploid and diploid varieties.

present investigation. In general, Stomatal frequency and size was found to be high

Stomatal frequency was correlated with drought resistance and disease resistance [11]. Further, the Stomatal frequency was found to be related to the dry weight of the aerial parts of the plants and diffusive resistance [12]. Smaller stomata with lesser frequency per unit area make mulberry leaves become more succulency, palatable and are suitable for silkworms. [13] reported that, moisture retention capacity will be higher in those mulberry varieties possessing smaller stomata and lower stomatal frequency. Similarly we found average more number of chloroplasts in the guard cells were found be 10–12 in diploids and uneuploids compared to the triploids and tetraploids 6–8. In diploids and uneuploids number chloroplast were

As mulberry is a heterogeneous, predominantly unisexual, cross-pollinated and as well as vegetatively propagated perennial plant, it exhibits a wide range of variations in each and every phenotypic characteristic. Often the same genotype reveals

The genotypic differences in trichome density observed in the present study provide evidence to such observations in the field. The dense cover of trichomes in shoot tip and leaves of diploids may pose resistance to thrips attack in diploid and uneuploid mulberry varieties. On the other hand shoot tip and leaves of triploid and tetraploid mulberry varieties are less protected with sparse trichome density and hence may become susceptible to the thrips attack. It is also reported that diploids has high drought tolerance capacity than triploids [14]. So the dense trichomes may provide a better barrier to excessive water loss than sparse

Trichomes are epidermal structures occur on stem, petioles & leaves. Diploid and uneuploid varieties showed highest trichomes density in both stem and leaves. On the other hand triploid and tetraploid varieties showed sparsh trichome density in both stem and leaves. Similar to various other anatomical feature cystolith frequency was lower in diploids and uneuploid compared to triploid and tetraploids. Triploids and Tetraploids showed distinctly high frequency and large sized cystolith, similar to stomatal frequency and size. In the evaluation of mulberry varieties the frequency and size of the idioblast has been taken as a parameter instead of

Varied chromosomal associations and configurations recorded in the present study indicate closer homology between associated chromosomes. Depending on the ploidy level and pairing of chromosomes bi-, tri- and quadrivalents showed in different cofigurational shape. In both diploid and uneuploid varieties the bivalents frequency was high and the regular univalent's appears to be a mere matter of chance. Most of the cultivated diploid mulberry varieties showed 14 bivalents at diakinesis and metaphase-I. Theoretically diploids should forms more bivalents in meiosis due to presence of two homologous chromosomes. Bivalents and univalents

In triploid varieties the trivalent frequency was high and low frequency of bi and univalent's and no higher chromosome configuration was found. On the contrary

The alignment of centromeres of trivalents and univalents appears to be random

and hence the assortment of chromosomes was also random. Hence majority of the cells showed unequal separation of chromosome at anaphase-I. Trivalents were

*DOI: http://dx.doi.org/10.5772/intechopen.97143*

almost double than triploids and uneuploid.

the presence of both and unlobed leaves.

frequency and size of cystolith [15].

**3.1 Chromosomal association and configuration**

were observed ' - - ' or " ͜͡ " and " -" types.

observed "- - -" or ">-' types.

some univalent's and bivalents were observed.

trichomes.

#### *Studies on Basic Chromosome Number, Ploidy Level, Chromosomal Association… DOI: http://dx.doi.org/10.5772/intechopen.97143*

present investigation. In general, Stomatal frequency and size was found to be high in tetraploid when compared to triploid and diploid varieties.

Stomatal frequency was correlated with drought resistance and disease resistance [11]. Further, the Stomatal frequency was found to be related to the dry weight of the aerial parts of the plants and diffusive resistance [12]. Smaller stomata with lesser frequency per unit area make mulberry leaves become more succulency, palatable and are suitable for silkworms. [13] reported that, moisture retention capacity will be higher in those mulberry varieties possessing smaller stomata and lower stomatal frequency. Similarly we found average more number of chloroplasts in the guard cells were found be 10–12 in diploids and uneuploids compared to the triploids and tetraploids 6–8. In diploids and uneuploids number chloroplast were almost double than triploids and uneuploid.

As mulberry is a heterogeneous, predominantly unisexual, cross-pollinated and as well as vegetatively propagated perennial plant, it exhibits a wide range of variations in each and every phenotypic characteristic. Often the same genotype reveals the presence of both and unlobed leaves.

The genotypic differences in trichome density observed in the present study provide evidence to such observations in the field. The dense cover of trichomes in shoot tip and leaves of diploids may pose resistance to thrips attack in diploid and uneuploid mulberry varieties. On the other hand shoot tip and leaves of triploid and tetraploid mulberry varieties are less protected with sparse trichome density and hence may become susceptible to the thrips attack. It is also reported that diploids has high drought tolerance capacity than triploids [14]. So the dense trichomes may provide a better barrier to excessive water loss than sparse trichomes.

Trichomes are epidermal structures occur on stem, petioles & leaves. Diploid and uneuploid varieties showed highest trichomes density in both stem and leaves. On the other hand triploid and tetraploid varieties showed sparsh trichome density in both stem and leaves. Similar to various other anatomical feature cystolith frequency was lower in diploids and uneuploid compared to triploid and tetraploids. Triploids and Tetraploids showed distinctly high frequency and large sized cystolith, similar to stomatal frequency and size. In the evaluation of mulberry varieties the frequency and size of the idioblast has been taken as a parameter instead of frequency and size of cystolith [15].

#### **3.1 Chromosomal association and configuration**

Varied chromosomal associations and configurations recorded in the present study indicate closer homology between associated chromosomes. Depending on the ploidy level and pairing of chromosomes bi-, tri- and quadrivalents showed in different cofigurational shape. In both diploid and uneuploid varieties the bivalents frequency was high and the regular univalent's appears to be a mere matter of chance. Most of the cultivated diploid mulberry varieties showed 14 bivalents at diakinesis and metaphase-I. Theoretically diploids should forms more bivalents in meiosis due to presence of two homologous chromosomes. Bivalents and univalents were observed ' - - ' or " ͜͡ " and " -" types.

In triploid varieties the trivalent frequency was high and low frequency of bi and univalent's and no higher chromosome configuration was found. On the contrary some univalent's and bivalents were observed.

The alignment of centromeres of trivalents and univalents appears to be random and hence the assortment of chromosomes was also random. Hence majority of the cells showed unequal separation of chromosome at anaphase-I. Trivalents were observed "- - -" or ">-' types.

*Cytogenetics - Classical and Molecular Strategies for Analysing Heredity Material*

**8**

**Figure 8.** *Variety Icheichei.*

**Figure 7.** *Variety Kokuso.*

**3. Micro-morphological features**

Stomata are the important anatomical and physiological characteristics of a leaf which control the rate of CO2 movement from air to the chlorophyllus tissue within the leaf and thereby influence the rate of CO2 exchange [10]. Stomatal size and frequency are important parameters in selecting drought resistant genotypes and these are also believed to regulate the leaf yield. As such, the Stomatal frequency has been studied in these taxa to correlate with cytological information recorded in the

In tetraploid varieties various types of chromosomal associations ranging from uni- to quadrivalents are observed during diakinesis and metaphase-I. Frequencies of quadrivalents are more than that of uni-, bi- and trivalents. However, the occurrence of multivalent such as tri- and quadrivalents indicates its polyploidy nature. Quadrivalents were observed " ͜͡ ͜͡ " or "- - - -" types.

Among different chromosomal associations, the bivalents in diploid and uneuploids, trivalents in triploid and quadrivalents in tetraploid were frequent. Majorities of quadrivalents were of ring type and other were chain types.

The concept of assessing the nature of polyploidy based on the sole criterion of multivalent frequency appears to have a limited value. Several workers have shown that, pairing of chromosomes is mainly governed by genes.
