Although dormancy in seeds of this species can be broken by scarification, they have physiological dormancy only. Further, based on information in the literature, it is concluded that it is unlikely that any species of Opuntia has physical dormancy. This is the first integrative study of the anatomy, dynamics of water uptake and dormancy in seeds of Cactaceae subfamily Opuntioideae.

Thioredoxins type h are classified into three subgroups. The subgroup II includes thioredoxins containing an N-terminal extension, the role of which is still unclear. Although thioredoxin secretion has been observed in animal cells, there is no evidence suggesting that any thioredoxin h is secreted in plants. In this study, we report that a thioredoxin h, subgroup II, from Nicotiana alata (NaTrxh) is secreted into the extracellular matrix of the stylar transmitting tract tissue. Fractionation studies showed that NaTrxh is extracted along with well characterized secretion proteins such as S-RNases and NaTTS (N. alata transmitting tissue-specific protein). Moreover, an NaTrxh-green fluorescent fusion protein transiently expressed in Nicotiana benthamiana and Arabidopsis thaliana leaves was also secreted, showing that NaTrxh has the required information for its secretion. We performed reduction assays in vitro to identify potential extracellular targets of NaTrxh. We found that S-RNase is one of the several potential substrates of the NaTrxh in the extracellular matrix. In addition, we proved by affinity chromatography that NaTrxh specifically interacts with S-RNase. Our findings showed that NaTrxh is a new thioredoxin h in Nicotiana that is secreted as well as in animal systems. Because NaTrxh is localized in the extracellular matrix of the stylar transmitting tract and its specific interaction with S-RNase to reduce it in vitro, we suggest that this thioredoxin h may be involved either in general pollenpistil interaction processes or particularly in S-RNase-based self-incompatibility.

Nitrogen concentration tended to be higher after the drier year and, while interannual variations in seed size and reserve composition were not sufficient to affect interspecific correlations among seed and seedling traits, some of the reserves were related to germination variables and seedling relative growth rate.

This study explores whether ecological factors, such as pollinators and pollen flow, or variation in pollen and ovule development account for the observed differences (approximately twofold) in the reproductive output of pin and thrum individuals of Erythroxylum havanense. The importance of ecological factors was assessed by means of comparison of the identity of pollinators and the rates of flower visitation, and by performing controlled hand pollinations and measurements of fruit set. In addition, we described the pollen and ovule development of thrum and pin individuals. Our results indicate that pollinators of E. havanense do not distinguish between floral morphs. The differences in fruit set between pin and thrum plants held even after hand pollination and, therefore, the observed differences in reproductive output between floral morphs of E. havanense cannot be explained in terms of asymmetrical pollen flow. There were no differences in the pattern of gynoecium development between the pin and thrum morphs, however androecium development showed marked differences between the morphs, and there was a resemblance between the developmental pathways leading to male sterility of the thrum morph of E. havanense with that of species with cytoplasmic male sterility (CMS).

Juvenile stages had no ant protection against herbivores probably due to resource limitation but also due to anatomical constraints. The results are consistent with the growth-differentiation balance hypothesis. As plants age, they increase in size and have larger nutrient-acquiring, photosynthetic and storage capacity, so they are able to invest in defence via specialized organs, such as EFNs. Hence, the more vulnerable juvenile stage should rely on other defensive strategies to reduce the negative impacts of herbivory.