**5. Genetic variations of areca plants in Indonesia and resistance to pathogens**

Diseases of areca nut attack the vegetative and generative organs. Vegetative organs that are the target of disease-causing pathogens include roots, stems, and leaves. Meanwhile, generative organs such as seeds, fruits, and flowers cannot be separated from the attack of pathogenic infections (**Table 1**).


#### **Table 1.**

*Areca nut varieties in Indonesia.*

New varieties are obtained from studying genetic diversity. One way to determine the diversity of a betel nut species is based on differences in morphological characteristics (either qualitatively or quantitatively) which are directly related to fruit production. Genetic diversity can be obtained by crossing, introduction, mutation, and selection of genetic sources. Selection based on morphological characters is a method that is often done. The selection was made on the morphological characteristics of the areca nut that were directly related to fruit production, namely the number of bunches, the number of fruit marks, and the number of spikelets [22]. Some of the morphological characteristics of areca nut that are often observed in genetic diversity research include stem height, stem circumference, number of leaf marks, number of leaves, number of bunches, number of fruit per bunches, whole fruit weight, fruit polar length, fruit equatorial length, fruit kernel weight, kernel polar length and kernel equatorial length [23]. One of the Pinang varieties in Indonesia which is classified as a superior variety is Pinang Betara. This variety received a recommendation from the government in the Decree of the Minister of Agriculture No. 199/Kpts/SR.120/1/2013. The characteristics of Pinang Betara include 1) dry kernel production/tree/year 5.70 kg, stem height reaches 10 meters, has 131.35 fruit/bunch, whole fruit weight is 47.06 grams, dry seed weight is 8.68 grams, high 9.79% tannin, has a dry kernel potential of 7.81 tons/hectare (**Figure 11**) [24].

The incidence of root rot can be caused by plant genetic factors so that the resistance response of each plant variety can be different [25]. Different genetic factors between plant varieties are derived from different inherited genes. Each variety has a different resistance to *S. rolfsii* fungus attack. The resistance properties found in each of these varieties are coded for resistance genes to fight pathogens. In other words, the resistance control genes possessed by each variety are different [26]. The Character of resistance to *Fusarium* sp. wilt disease. Judged by several things: 1) disease period value (day after inoculation), 2) disease incidence (%) and 3) endurance category (units/day). According to this study, a longer incubation period correlates with lower disease incidence and slower infection rates [27].

#### **Figure 11.**

*Several varieties of areca nut in Indonesia, from Sumatra Island: (A) Pinang Wangi, (B) Pinang lokal [23], (C) Pinang Betara [22], from Sulawesi island: (D) Pinang Duhia Da'a-Gorontalo, Tingkohubu, Huntu I, Huntu II, Huntu III [19].*

### **6. Conclusion**

Diseases in plants can be caused by an imbalance of environmental conditions, pathogens with high pathogenicity, and susceptible hosts. These three factors trigger disease severity in plants. This paper describes sixteen diseases in areca nut caused by the presence of pathogens, infection cycle and chain, plant defense response, as well as genetic variation affects plant resistance to pathogens.

#### **Acknowledgements**

The author would like to thank the head of the biology department, the Dean of the Faculty of Science and Technology, and The Rector of Universitas Islam Negeri Ar-Raniry Banda Aceh, Indonesia who has allowed the author to contribute to this chapter of the book.

#### **Conflict of interest**

The authors declare no conflict of interest.

*Plant Diseases of Areca Nut DOI: http://dx.doi.org/10.5772/intechopen.107504*
