Keanekaragaman Morfologi dan Sitologi Begonia hooveriana Wiriad. di Pulau Sulawesi
Abstract
Jenis ini memiliki variasi dan kisaran ciri morfologi yang lebar mengakibatkan batasan jenis menjadi kompleks, sehingga perlu dilakukan peninjauan kembali status taksonominya. Penelitian ini bertujuan meninjau kembali status taksonomi B. hooveriana berdasarkan keanekaragaan morfologi dan sitologi. Pengamatan morfologi dilakukan pada 66 individu yang telah dikoleksi dari Sulawesi Tengah (Wera, Saluki), Sulawesi Barat (Sepang), Sulawesi Selatan (Londa, Tilanga, Gandangbatu, Makale, Baroko, Bambapuang, Kebun Raya Enrekang, dan Tana Toraja) dan ditambah dengan spesimen dari Herbarium Kebun Raya Bogor (KRB). Ciri morfologi yang diamati yaitu 27 karakter vegetatif dan 54 karakter generatif. Pengataman sitologi dilakukan dengan cara memeriksa kromosom somatik pada ujung akar dengan menggunakan metode squash. Konstruksi dendrogram menggunakan metode Unweighted Pair Group Method with Arithmatic Average (UPGMA) melalui program Numerical Taxonomy and Multivariate Analisys System (NTSys) versi 2.1.1a. Analisis komponen utama (principal component analysis/PCA) dan korelasi pearson pada Begonia hooveriana adalah salah satu Begonia endemik dari Pulau Sulawesi. program Minitab 19. Data sitologi didokumentasi, dianalisis jumlah, ukuran, dan bentuk kromosomnya. Pengukuran kromosom menggunakan perangkat lunak ImageJ dan konstruksi ideogram menggunakan perangkat lunak MS visio. Dendrogram berdasarkan ciri morfologi membagi B. hooveriana menjadi tiga kelompok dengan koefisien kesamaan berkisar 0,24−0,96. Ciri morfologi yang memisahkan ketiga kelompok yaitu bentuk tepal bunga jantan, ukuran tepal bunga jantan, bentuk pangkal tepal bunga jantan, jumlah benang sari dalam satu androesium, panjang tangkai sari, panjang gagang perbungaan betina, panjang gagang buah, panjang tangkai bunga betina, panjang tangkai buah, bentuk bakal buah, lebar bakal buah terlebar, bentuk buah dan bentuk ujung buah. Kromosom B. hooveriana memiliki kariotipe yang bervariasi, menunjukkan adanya 3 kelompok yaitu 2n = 30 = 15 m (Sulawesi Tengah), 2n = 30 = 14 m + 1 sm (Sulawesi Barat), dan 2n = 30 = 13 m + 2 sm (Sulawesi Selatan). Hal ini sejalan dengan hasil pengamatan morfologinya. Dengan demikian berdasarkan karakter morfologi dan sitologi B. hooveriana terdiri atas tiga varietas, yaitu Begonia hooveriana var. hooveriana, Begonia hooveriana var. khansanuum, dan Begonia hooveriana var. rubescence. Dua varietas terakhir merupakan varietas baru yang ditentukan dalam penelitian ini. Begonia hooveriana is one of the endemic Begonias of Sulawesi Island. This species has a wide variety and range of morphological characteristics, resulting in complex species boundaries. For this reason, it is necessary to review their taxonomic status. This study aims at assessing the taxonomic status of B. hooveriana based on its morphological and cytological diversity. In this study, morphological observations were conducted on 66 individuals collected from Central Sulawesi (Wera, Saluki), West Sulawesi (Sepang), and South Sulawesi (Londa, Tilanga, Gandangbatu, Makale, Baroko, Bambapuang, Enrekang Botanical Gardens, and Tana Toraja), added with specimens from the herbarium of Bogor Botanical Gardens. The observed morphological characteristics were 27 vegetative characters and 54 generative characters. Apart from that, cytological observations were carried out by examining the somatic chromosomes at the root tips using the squash method. Furthermore, the dendrogram was constructed using the Unweighted Pair Group Method with Arithmetic Average (UPGMA) through Numerical Taxonomy and Multivariate Analysis System (NTSys) v. 2.1.1a. Principal component analysis/PCA and Pearson correlation were run in the Minitab 19 program. Cytological data were documented. Moreover, the number, size, and shape of chromosomes were analyzed. The chromosomal measurement was performed using ImageJ software, while the ideogram construction was through MS Visio software. The dendrogram, based on morphological characteristics, divided B. hooveriana into three groups with similarity coefficients ranging from 0,24 to 0,96. The morphological characteristics that separate the three groups were the shape and base shape, size of the male flower tepals, the number of stamens in one androecium, the length of filament, female inflorescence and fruit peduncle, length of female flower and fruit pedicels length, shape and widest point ovary, fruit shape, and apex. Chromosomes of B. hooveriana have varied karyotypes, indicating the presence of 3 groups: 2n = 30 = 15 m (Central Sulawesi), 2n = 30 = 14 m + 1 sm (West Sulawesi), and 2n = 30 = 13 m + 2 sm (South Sulawesi). This is in line with the results of morphological observations. Therefore, based on the morphological and cytological characteristics, B. hooveriana has three varieties: Begonia hooveriana var. hooveriana, Begonia hooveriana var. khansanuum, and Begonia hooveriana var. rubescence. The last two varieties are new varieties found in this study.