average and record yields. Those crops having marketable vegetative structures exhibited approximately threeCrops with economically valuable reproductive structures show fold reductions in yield (Boyer, 1982). These data sugthe greatest negative discrepancy between average and record yields. gest that plants have high productivity potential but are To alleviate environmental stress–related yiel...

We have found that the most probable cause of the leakage seen when dry cells or organisms such as seeds, pollen, or yeast cells are plunged into water is a gel to liquid crystalline phase transition in membrane phospholipids accompanying rehydration. By using Fourier transform infrared spectroscopy we have recorded infrared spectra of CH(2) stretching vibrations in dry and partially hydrated i...

Selenium (Se) is an essential micronutrient for many organisms, but is also a toxin and environmental pollutant at elevated levels. Due to its chemical similarity to sulphur, most plants readily take up and assimilate Se. Se accumulators such as Brassica juncea can accumulate Se between 0.01% and 0.1% of dry weight (DW), and Se hyperaccumulators such as Stanleya pinnata (Brassicaeae) contain be...

The ornate surfaces of male and female reproductive cells in flowering plants have long attracted attention for their variety and evolutionary significance. These structures, and the molecules involved in sexual interactions, remain among the most rapidly evolving and diverse characteristics known. As varied as they may be, each element takes part in performing the same functions, protecting po...

The pollen-specific receptor kinases LePRK1 and LePRK2 have localization and expression profiles that strongly suggest they play roles in pollen germination and tube growth. To identify downstream components of LePRK signaling, we used their cytoplasmic domains (CDs) as baits in yeast two-hybrid screens of a tomato pollen cDNA library. A pollen-specific protein we named kinase partner protein (...

Differential screening of a mature Brassica campestris pollen cDNA library has identified five cDNA clones that represent transcripts expressed exclusively, or at elevated levels, in pollen. We show here that the expression of one of these, clone Bcp1, is tissue specific and temporally regulated. The gene is activated during microspore development, as detected by in situ hybridization. Expressi...

Many tests for pollen viability have been proposed. The ability to determine this reproductive state in the field can be very important in botanical research as well as for horticultural purposes. After reviewing a large number of tests, we compared four methods of determining pollen viability. Each of these methods can easily be carried out in the field. Viability tests were carried out on 17 ...

In Brassica , the thioredoxin h proteins, THL1 and THL2, were previously found to be potential inhibitors of the S receptor kinase (SRK) in the Brassica self-incompatibility response. To investigate the biological roles of THL1 and THL2 in pollen-pistil interactions, the stigma-specific SLR1 promoter was used to drive antisense THL1/2 expression in Brassica napus cv. Westar. This cultivar is no...