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HighlightMaize Kip-related proteins can be differentially phosphorylated by different cyclin D–cyclin-dependent kinase complexes and this influences their performance as cyclin-dependent kinase inhibitors.

Maize CycD3;1 associates to CDKA or CDKB1;1 proteins during germination and the complexes formed develop kinase activity. These complexes appear to vary in size as germination proceeds, suggesting association to different sets of proteins. CycD3;1 and associated CDK proteins respond to phytohormones and sucrose. Results revealed a reduction in the CycD3;1 protein amount along germination in the presence of indoleacetic acid (IAA) or abscisic acid (ABA), although in the latter protein levels recover at the end of germination. While the levels of CDKA increase with IAA, they decrease with ABA. Both phytohormones, IAA and ABA, increase levels of CDKB1;1 only during the early germination times. CycD3;1 associated kinase activity is only reduced by both phytohormones towards the end of the germination period. On the other hand, lack of sucrose in the imbibition medium strongly reduces CycD3;1 protein levels without affecting the levels of neither CDKA nor CDKB1;1. The corresponding CycD3;1 associated kinase activity is also severely decreased. The presence of sucrose in the medium appears to stabilize the CycD3;1 protein levels.

<p><strong>Background: </strong><em>Agave potatorum</em> reproduces mainly through seeds is widely collected for the mezcal production, and there is currently a marked decrease in their wild populations. Therefore, to contribute to its sustainable use, it is important to characterize the morphology of its seeds and to know their germinative characteristics.</p><p><strong>Research question:</strong> Do the year and the collection site have an effect on the size, color, viability and germination capacity of <em>Agave potatorum</em> seeds?</p><p><strong>Species studied</strong>: <em>Agave potatorum</em> Zucc.</p><p><strong>Study site and period of research:</strong> Seeds of <em>Agave potatorum</em> were collected in Oaxaca, Mexico: Miahuatlán (MIAH), in 2014; Coixtlahuaca (COIX), in 2015; and Zaachila (ZAA), in 2015 and 2016.</p><p><strong>Methods:</strong> For the seeds, we analyzed four physical descriptors, five color coordinates, and nine germination variables. We used a completely randomized design with four replications (100 seeds). An analysis of variance, a comparison of means, and a linear correlation analysis were performed.</p><p><strong>Results:</strong> We found that the ZAA16 seeds showed the highest values (<em>P</em> &lt; 0.05) for weight and size, and for the luminosity coordinate (L*, 15.2). Color coordinate values revealed a black color of the seeds, which significantly diminished in luminosity with seeds age and varied with their origin. The coordinate L* was correlated significantly with the total dry weight of seedlings and seed volume.</p><p><strong>Conclusions:</strong> <em>Agave potatorum </em>seeds significantly changed their physical dimensions and germination capacity according to their origin. The luminosity of the black color of seeds decreased with seed age and was correlated with seed volume and seedling total dry weight.</p>

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