Morphological descriptors and ISSR molecular markers in the evaluation of genetic variability of Tectona grandis genotypes

Abstract

ABSTRACT. This study aimed to evaluate the genetic variability of the teak germplasm bank, using morphological traits and inter-simple sequence repeat molecular markers. Thirty clones were evaluated in a randomized complete block design with three replicates, and each plot was composed of three plants. A joint analysis of quantitative and qualitative variables was performed using the Gower algorithm. Quantitative, qualitative, and molecular variables were analyzed simultaneously using the Ward-MLM procedure. There is genetic variability among the 30 teak genotypes studied, considering the quantitative, qualitative, and molecular variables by the Ward-MLM statistical procedure. Morphological traits used proved to be efficient for the study of genetic variability; however, it was not possible to compose a descriptor table for clonal teak genotypes based on the traits evaluated. The Gower method was efficient in discriminating the groups, demonstrating that the simultaneous analysis of qualitative and quantitative data is feasible and can allow greater efficiency in the knowledge of the variability among teak genotypes. The genotype 22 showed to be the most divergent compared to the other genotypes, except for the cluster of genotypes by the UPGMA method based on the Gower distance obtained by the Ward-MLM procedure, which formed a group with genotypes 9 and 30, in the morphological and molecular analyses and was grouped alone.

MORPHOLOGICAL DESCRIPTORS FOR THE CHARACTERISATION OF TEAK CLONES CUTTINGS (Tectona grandis L.F.)

“…The cuttings at 30 and 120 days of age stood out, because they showed the highest number of traits (12 and 11, respectively) for the diff erentiation clones. Previous studies on the subject failed to assess the diversity from cuttings of diff erent genotypes, nor a descriptive table (Chimello et al, 2017).…”

“…The genotypes with greater similarity were grouped together regardless of their origin (Solomon Islands, Brazil-Cáceres, Indonesia, Malaysia, and Tanzania). Some clones may share similarities that are not associated precisely to their places of origin (Fofana et al, 2009;Chimello et al, 2017). Also, the similarity of the morphological traits between some genotypes can result from more closely related populations (Da Costa et al, 2014), while others may be similar or divergent in genotypes with the same or diff erent origins (Alcântara and Veasey, 2013;Alcântara et al, 2016).…”

“…In breeding programs, genotypes with similar morphological traits experience fewer benefi ts that result from the combination and genetic gain (Chimello et al, 2017;Prasetyo et al, 2020) when compared to phenotypically divergent genotypes (Alcântara and Veasey, 2013;Chimello et al, 2017;Flôres Junior et al, 2018). Therefore, in potential future breeding programs, it is important to consider the dissimilarity of genotypes to obtain higher genetic gains per generation (Chawhaan et al, 2003;Vasudeva et al, 2004;Chaudhari et al, 2018;Huang et al, 2019).…”

“…The genotype characterization of cultivated plants contributes in breeding programs and in the process of cultivar protection (Alcântara et al, 2016;Chimello et al, 2017). The protection of a new cultivar is the result of genetic improvement and its identifi cation should be possible through morphological traits: distinguishability, homogeneity, and stability -DHS (Santos and Pacheco, 2011).…”

“…In the case of perennial species such as teak, the use of seedlings brings advantages such as the early evaluation of the genetic material, requiring less space for its establishment and fewer fi nancial resources for evaluations. Some studies using teak clones at diff erent ages, allowing the diff erentiation among groups of genotypes and origins, also evaluating their genetic variability (Miranda, 2013;Gunaga et al, 2013;Baretta, 2016;Alcântara et al, 2016;Chimello et al, 2017). However, these studies did not defi ne a descriptor table for teak clones.…”