Augusto R, Maranho R C, Mangolin C A, Filho J C Bespalhok, Machado M F P S
Programa de Pós-Graduação em Genética e Melhoramento, Universidade Estadual de Maringá, Maringá, PR, Brasil.
Programa de Pós-Graduação em Agronomia, Universidade Estadual de Maringá, Maringá, PR, Brasil.
Genet Mol Res. 2017 Mar 8;16(1):gmr-16-01-gmr.16019519. doi: 10.4238/gmr16019519.
The reduction in sugarcane productivity in subsequent cutting stages may be related to a gradual decrease of the allele number and mean observed heterozygosity (H) in the sugarcane ratoon. This hypothesis was tested assessing the number of alleles and H values in 10 expressed sequence tag microsatellites (Est-SSR loci) of the sugarcane varieties RB72454 and RB867515 in different cutting stages. Changes of allele numbers in samples of different cutting stages were observed in seven and six EstSSR loci of the RB72454 and RB867515 varieties, respectively. Reduction of allele numbers was observed in the samples collected in the fourth and sixth cutting stages of the RB72454 variety. In contrast, an increase of the allele numbers was detected in the samples collected on fourth, sixth, and seventh cutting stages of the RB867515 variety. Unchanged allele numbers were observed only in EstB41, EstC84, and EstB130 loci of the RB72454 variety, and EstB41, EstC67, EstA68, and EstB130 loci of the RB867515 variety. The variety RB867515 has lower polymorphism and values of H than the RB72454 variety in different stages of cutting. At molecular level, in Est-SSR loci, the RB72454 variety showed higher changes in subsequent stages of cutting than RB867515. The similarities and divergences at molecular level between varieties RB72454 and RB867515 observed in the 10 Est-SSR loci during subsequent cutting stages can not explain the reduced productivity frequently observed after subsequent cutting stages but showed that phenotypic and physiological changes after each cutting stage are also accompanied by changes at genomic level.
在后续砍收阶段甘蔗生产力的下降可能与甘蔗宿根中基因座数量和平均观察杂合度（H）的逐渐减少有关。通过评估甘蔗品种RB72454和RB867515在不同砍收阶段的10个表达序列标签微卫星（Est-SSR基因座）中的基因座数量和H值，对这一假设进行了验证。在RB72454和RB867515品种的7个和6个EstSSR基因座中，分别观察到不同砍收阶段样本中基因座数量的变化。在RB72454品种的第四和第六砍收阶段采集的样本中观察到基因座数量减少。相比之下，在RB867515品种的第四、第六和第七砍收阶段采集的样本中检测到基因座数量增加。仅在RB72454品种的EstB41、EstC84和EstB130基因座以及RB867515品种的EstB41、EstC67、EstA68和EstB130基因座中观察到基因座数量不变。在不同砍收阶段，RB867515品种的多态性和H值低于RB72454品种。在分子水平上，在Est-SSR基因座中，RB72454品种在后续砍收阶段的变化比RB867515品种更大。在后续砍收阶段，在10个Est-SSR基因座中观察到的RB72454和RB867515品种之间分子水平上的异同，无法解释在后续砍收阶段经常观察到的生产力下降，但表明每个砍收阶段后的表型和生理变化也伴随着基因组水平的变化。
