Pólen 2n e mecanismos meióticos de formação em Solanum commersonii ssp

Abstract

RESUMOSolanum commersonii subsp. Termos para indexação: Batata, pólen não reduzido, melhoramento genético vegetal. ABSTRACTSolanum commersonii subsp. commersonii Dun. and Solanum commersonii subsp. malmeanum Bitt. (2n=2x=24 -1EBN) cannot be directly crossed with the cultivated Solanum tuberosum subsp. Tuberosum L. (2n=4x=48 -4EBN) species due to ploidy barriers and endosperm balance number (EBN). However, non-reduced pollen production by the wild species S. commersonii ssp. (2x=2n=24 -1EBN), allows the crossing of these species with dihaploids of potato and with the diploids species, S. phureja Juz.&Bukasov. and S. chacoense Bitt., all with 2EBN. The aim of this work was to determine the meiotic mechanism and frequency of non-reduced pollen production of five clones of S. commersonii ssp. Three different clones of S. commersonii subsp. commersonii Dun. (SCC) and two of S. commersonii subsp. malmeanum Bitt. (SCM) were evaluated. In the evaluation, two hundred viable pollen grains were stained (2% acetic carmin) and measured. The pollen grains measuring 25 µm in diameter or more were considered nonreduced. The clone Solanum commersonii subsp. commersonii Dun. (SCC 100) produces 26.1% of non-reduced pollen grains caused by parallel spindles and fusion spindles, which may be used in breeding program.

Searching for mechanisms behind meiotic abnormalities in Crotalaria spectabilis Roth

“…Both types of spindle mis-orientation can generate non-reduced gametes (2n) (Pagliarini, 2000;Blasio et al, 2022). The production of unreduced gametes through these mechanisms has already been reported in Solanum L. (Andreuzza;Siddiqi, 2008;Tomé et al, 2009), Arabidopsis thaliana (L.) Heynh (D'Erfurth et al, 2008), Medicago L. (Barcaccia et al, 1995) and Saccharum L. (Bhat;Gill, 1985). In some species, these spindle abnormalities are controlled by specific genes, like Atps1 in Arabidopsis thaliana (D'Erfurth et al, 2008), ps and pc in Solanum phureja Juz.…”

Solanum malmeanum, a promising wild relative for potato breeding

“…Some accessions of S. malmeanum showed regular meiotic abnormalities observed at microsporogenesis, including chromosomes out of the equatorial plate in metaphases I and II (MI and MII) and lagging chromosomes in anaphases I and II, and telophases I and II ( Pandolfi, 1998 ; Tomé et al., 2007 ; Tomé et al., 2009 ). Furthermore, a range from 3.7% to 50.8% of pollen mother cells (PMC) with meiosis abnormalities was observed.…”

“…Although the accessions SCM57 (BGB017) and SCM60 (BGB447) ( AleloVegetal, 2022 ) did not show unreduced pollen grains, they had meiotic mechanisms (parallel spindles) that possibly can lead to the formation of unreduced pollen, presenting the highest percentages of cells with parallel spindles (27% and 22%). Furthermore, pollen grain size of S. commersonii (13.68–35.52 µm) tends to be larger than that of S. malmeanum (11.4 to 23.9 µm) ( Tomé et al., 2009 ). This approach put forward by Tomé et al., (2009) raises the hypothesis that S. malmeanum has no pollen grain diameters satisfying the value of 25 µm suggested by Quin et al.…”

“…Furthermore, pollen grain size of S. commersonii (13.68–35.52 µm) tends to be larger than that of S. malmeanum (11.4 to 23.9 µm) ( Tomé et al., 2009 ). This approach put forward by Tomé et al., (2009) raises the hypothesis that S. malmeanum has no pollen grain diameters satisfying the value of 25 µm suggested by Quin et al. (1974) and Ramanna (1974) and would imply the proposition of a new threshold for unreduced (2n) pollen grains.…”